1. Field of the Invention
The present invention relates to data delay devices, and more particularly to a solid state delay device for digital data.
2. Description of the Prior Art
In aerospace applications there are many situations where telemetry data is not immediately available on the ground, either due to the aerospace vehicle not being within range of a ground station or due to the blackout periods associated with missile staging or capsule reentry into the earth's atmosphere. To retrieve this lost telemetry data magnetic recording devices, such as in-flight tape recorders, have been used to record the telemetry data and then replay the recorded data either automatically or upon command from the ground station. Tape recorders have a limited shelf life. Lubricating oil in the bearings runs out due to lack of use. Exercising or use of the recorder to maintain lubrication causes tape wear due to record head/tape friction. The tape wear before flight has to be limited, making the recorder a limited life item.
The aerospace environment is also detrimental to the in-flight tape recorder with its moving parts due to rapid vehicle attitude changes which affect the tape. The tape momentum prevents the tape from changing direction as rapidly as the vehicle attitude changes, resulting in added wear on the moving parts and in damage to the tape. Thus, aerospace tape recorders have a basic application deficiency and redundancy is required in the event one recorder is damaged beyond use in flight.
Thus, it is desirable to develop a storage medium for aerospace vehicle digital data which eliminates moving and limited life parts.